CTA Neck & Head
Gibo and Rhoton’s ICA Classification
C1 is the cervical portion of the ICA from its origin to its entry into the external orifice of the carotid canal.
C2 is the petrous portion of the artery from the external orifice of the carotid canal to the entry of the ICA into the cavernous sinus.
C3 corresponds to the cavernous portion of the artery from its entrance in the posterior part of the cavernous sinus to its exit near the anterior clinoidal process (Images below).
C4 is the supraclinoid portion of the ICA that was divided by Gibo et al. in 3 distinct parts.
Segmental Classification of the Internal Carotid Artery: An Overview: Contemporary Neurosurgery
ICA Start
Petrous
Cavernous
Cavernous
Supraclinoid
Supraclinoid
M1
A1 & ACA
ACA A2
Anterior Circulation
Left Subclavian
Vert Origin
V1(pre-foraminal)
V2 (foraminal)
V3 (atlantic, extradural or extraspinal)
V4 (intradural or intracranial)
Basilar
Superior cerebellar artery (SCA)
PCA/PCOM
PCA
Posterior Circulation
Neck
Bovine Arch
Bovine arch is the most common variant of the aortic arch and occurs when the brachiocephalic (innominate) artery shares a common origin with the left common carotid artery.
(Don't use the word bovine in the dictation)
Left Vert from arch
Four branches from the aortic arch arch are noted, with the third branch being the left vertebral artery.
Calculate Carotid Stenosis
NASCET was established by angiographic calculation of ICA stenosis percentage using the following formula:
% ICA stenosis = (1 - [narrowest ICA diameter/diameter normal distal cervical ICA]) x 100
The European Carotid Surgery Trial (ECST) also demonstrated benefits for carotid endarterectomy in patients with symptomatic higher than 80% ICA stenosis 3.
Ulcerated carotid atherosclerotic plaque
Head
Fetal Origin of the PCA
The term is used variably, when the bulk of PCA flow comes from the anterior circulation (internal carotids) via a robust post. communicating artery.
Clinically, it is important to know when there is a fetal PCA, as an embolic infarct in the occipital lobe would be related to the anterior circulation in this setting. It also may affect approach and feasibility for an intravascular versus surgical intervention of aneurysm.
Head and Neck Radiology
Great if you like well labeled images
